Control of AC Motor through VFD with Modbus communication via Labview

[Alexis_Koul]

Hello everyone,

I need to control my three phase AC Motor thought VFD. I have already download the Modbus Library and I have written the initial code in the Labview.

I have seen similar post regarding controlling an AC motor with Modbus and Labview.

A very good post that I have read, have from the VFD manual the Modbus Decimal and Octal. In my VFD I dont have any of those. I am using the GK3000 VFD. In my case, I have info as the attached photo shows.

Any comment is appreciated. 

Regards,
Alexis

[Alexis_Koul]

Hello,

The issue that you had 3 years ago is similar to mine today 😊.

I would like to ask you the following questions:
1)How do you decided the number of <<Write Single Holding Register>>?

2)The address and input data for each one of them?

Thank you!
Regards,
Alexis

[GerdW]

Hi Alexis,

so what is your actual problem?

Can you read any data from your VFD?

[Alexis_Koul]

Hello,

Thank you for your reply. These are data from other VFD (attached photo)
In mine VFD manual, I dont have any of those.... The link below is the manual.

https://www.ato.com/Content/doc/GK3000-VFD-user-manual.pdf

[GerdW]

Hi Alexis,

it's all explained in your manual, starting at chapter 9/page 128…

[Alexis_Koul]

Hello Gerd,

Thank you for you reply. Yes I have seen that but I cant find the Modbus decimal. Could you please be more specific which part of the pages that you told me to emphasize?

Thank you for your help.

Alex

[GerdW]

Hi Alexis,

that VFD is set to ASCII mode by default. Usually Modbus/RTU is used with serial ports, so you have to change this setting on your VFD.

Starting from page 128 the messages and supported commands are described, with an example for ASCII and RTU mode each. The VFD only supports the Read and Write commands, and for both you just have to give the register number you want to access - as explained in the example data structures in that manual…

(Please don't start the discussion about your problem in several places: keep information in just one place/thread!)

[Alexis_Koul]

Hello GerdW,

First let me thank you for taking the time to reply on my questions. Regarding the post of the other person, he/she putted the following:

I cannot understand why he/she added 5 "write single holding", and how you come in the idea that you need 5....

Also the input data and the address is changing for each one of those. How you are coming in those values..??

Will be extremely glad if you can answer me those questions.

-Alex

[GerdW · Accepted solution]

Hi Alexis,

---

@Alexis_Koul wrote:

I cannot understand why he/she added 5 "write single holding", and how you come in the idea that you need 5....
Also the input data and the address is changing for each one of those. How you are coming in those values..??

---

This other person is writing 5 different values to 5 different registers/addresses.

Why did (s)he do this? Probably there was a requirement to set just 5 registers to specific values…

Where did (s)he get the register address from? Most probably from the manual of the device…

Your manual also list several addresses and their meaning. Just use them!

[Tamir87]

I'm attaching a vi that I built in order to set the speed for a Nidec M200 VFD through modbus com protocol. 
I used usb to 485 converter. 

it might be useful for you.